There doesn't seem to be any upcoming workshops specifically focused on composting based on the available council information. However, there is a general emphasis on sustainability and environmental events in Guildford, which might include related activities.
For information on gardening and composting, you can explore resources from the Surrey Environment Partnership or consider joining broader sustainability events, which might touch on composting topics. If you're looking to learn more about composting techniques, visiting the Surrey Environment Partnership website might be a useful next step.